The Complex Relationship Between Beans, Peas and Gallstones


The Complex Relationship Between Beans, Peas and Gallstones

Years ago, it was reported that people given 120 g of legumes per day for three months experienced a significant increase in bile saturation (110 to 169% elevation).(1) Such an increase would almost certainly elevate the risk of forming gallstones. This association supports the epidemiologic link between beans and gallstones in Pima Indians and Chileans -- two groups not eating Western diets but nonetheless having a high incidence of gallstone formation. Not all research corroborates a link between legumes and gallstones, however; at least one study found that gallstone patients ate fewer beans than healthy controls.(2)

A recent report from the Journal of Lipid Research not only corroborates a link between long-term (six to seven weeks) administration of 120 g of legumes per day and increased bile saturation (in this case, an 18% elevation), but also for the first time explains the relationship in a way that makes physiologic sense.(3)

Bean intake is associated with lowered serum cholesterol -- a finding that many nutritionally oriented doctors assume is primarily a function of the effect of soluble fiber found in beans on absorption of fats from the gut. The new report shows that legume consumption lowered LDL-C by shunting cholesterol into bile. This effect explains the hypolipidemic effect of eating legumes: cholesterol is leaving the blood stream. It also explains the effect legumes have on saturation of bile with cholesterol -- because that's where the cholesterol is apparently going. (An increase in bile saturation means a relative increase in biliary cholesterol compared with bile acids and lecithin; any elevation in bile saturation increases the risk of stone formation; gallstones are primarily made up of cholesterol, and bile acids and lecithin dilute the cholesterol, thus reducing the chance for precipitation.)

The bottom line here is dichotomous. It's appropriate to recommend increasing legume intake for people at risk for cardiovascular disease. By lowering serum LDL-C, legumes will most likely reduce their risks. But until more is known, it appears wise to do the opposite for people with gallstones.

(1) Nervi F, Covarrubias P, Bravo N, et al. Influence of legume intake on biliary lipids and cholesterol saturation in young Chilean men. Gastroenterol 1989; 96:825-30.

(2) Maclure KM, et al. Dietary predictors of symptom-associated gallstones in middle-aged women. Am J Clin Nutr 1990; 52:916-22.

(3) Duane WC. Effects of legume consumption on serum cholesterol, biliary lipids, and sterol metabolism in humans. J Lipid Res 1997; 38:1120-8.

Natural Product Research Consultants, Inc.


By Steve Austin

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